Telematics safety and security services (TSSS) can be provided in vehicles to automatically place a call to summon emergency services in the event of an accident. For example, Ford Motor Company offers a vehicle telematics control unit (e.g., a Ford SYNCH™ unit) that is a factory-installed, integrated in-vehicle communications and entertainment system that can be tethered to the user's cell phone (e.g., via Bluetooth® radio connection) to control automated calls for 911 assistance, as well as allow users to make hands-free telephone calls, control music and perform other functions with the use of voice commands. In the event that a vehicle airbag is deployed, the vehicle telematics unit can automatically initiate an automatic collision notification (ACN) call to Enhanced 911 (E911) emergency authorities via a public safety answering point or public-safety access point (PSAP). It is important that the correct vehicle location is provided to the emergency operator during an ACN call because this information is used to direct emergency services to the location of the vehicle.
An example E911 system for handling a wireless E911 call from a mobile TCU such as a Ford SYNCH™ unit is shown in FIG. 1A. As explained below, emergency response operations of existing E911 systems can be negatively impacted by inaccurate and sometimes conflicting call location information.
A PSAP 170 is a call center responsible for answering calls to an emergency telephone number (e.g., 9-1-1 in the United States) or other telephone number designated for requesting police, firefighting and ambulance services. A PSAP 170 generally employs human operators who are trained to dispatch these emergency services depending on information received via the emergency call. There are a number of PSAPs in the United States (e.g., approximately 6100 PSAPs serving different geographical areas or jurisdictions that may overlap), and they are usually funded and maintained by a government agency or public entity (e.g., a county, a large city, or a municipality). Most PSAPs have a regional Emergency Service Number (ESN) or other number identifying the PSAP 170. Enhanced 9-1-1 or E911 refers to the ability of PSAP equipment to display to the operators such information as callback number of calling party, wireless carrier name and cell sector address or other location information. As explained below, because PSAPs are generally publically funded (i.e., unlike commercially owned and operated call centers), they are not as easily upgraded to process improved location information provided by the calling telematics control unit and/or the wireless network.
With reference to FIG. 1A, E911 calls from persons requiring emergency services are generally routed to a selected PSAP based on caller location by a 911 selective router 160 that can access a database of PSAP information (not shown). For example, for wireline 911 calls, the customer number (i.e., automatic number identification or ANI assigned to that customer) is associated with a particular ESN in the 911 selective router database. For wireless 9-1-1 calls, however, a pseudo-ANI or p-ANI is assigned to each sector of a cell site 110, and the p-ANIs are associated with a particular PSAP ESN in the database for routing according to E911 Phase I described below. That is, a wireless 9-1-1 call is initially received at a cell site 110 which is a radio transceiver base station that acts as a point of entry for calls from wireless devices into a wireless carrier's telecommunications network. The geographical area served by a cell site is divided into coverage areas of one or more sectors (e.g., receiving antennas on the base station or tower). For example, cell site with 1 sector (Omni) is common in rural areas where maximum coverage is most desired; whereas a cell site with three or more sectors is common in urban areas where call volume is more of an issue.
The database of PSAP information (not shown) employed by the selective router 160 can also allow determining the appropriate PSAP based on cross-referencing stored PSAP locations such as street addresses and/or corresponding earth coordinates (e.g., longitude and latitude) with coordinates of a wireless phone if available. Using an ANI or p-ANI or phone coordinates, the 911 selective router 160 can access and retrieve a corresponding ESN from the database to route the 911 call to the appropriate PSAP 170. Calls can also be relayed between PSAPs when, for example, a city operates its own PSAP but not its own particular emergency service (e.g., the city has a city police force but relies on a county-funded fire department).
In contrast to the wireless network depicted in FIG. 1A, when a wireline phone is used to call 9-1-1 via the public switched telephone network (PSTN) (i.e., a wireline enhanced 911 call is placed), the 911 call from the wireline telephone is sent to a local central office that serves that specific telephone. The central office processes a 911 call by forwarding the call to a selective router (e.g., 911 selective router 160). The 911 selective router, in turn, routes the voice associated with the call, as well as data comprising the caller's telephone number or ANI to an appropriate PSAP. As stated above, the 911 selective router uses the ANI to look up the ESN of the appropriate call center (i.e., PSAP) in the E911 selective router database and connect the call. Caller address information is not passed along by the public phone network, that is, only the caller's phone number or ANI is passed. The PSAP uses the calling party number to look up the address in an Automatic Location Identification (ALI) database 150. Most ALI databases have a companion database known as the Master Street Address Guide (MSAG). The MSAG describes the exact spelling of streets, street number ranges, and other address elements. When a new PSTN telephone customer account is created, for example, the customer billing address, for example, is looked up in the MSAG to find the appropriate ESN that 911 calls from that phone number should be routed to. If the phone number is not passed, or the phone number is not in the ALI database (i.e., “ALI Failure” occurs), the call is then passed to the trunk group's default ESN, which is a PSAP designated for this function. The PSAP operator must then ask the incoming caller for their location and redirect them to the correct PSAP.
Unlike wireline enhanced 911 calls, when a wireless enhanced 911 call is made as illustrated in FIG. 1A, the billing address associated with a cell phone is not necessarily the location to which emergency responders should be sent, since the device is portable. This means that locating the caller is more complicated than merely using an ANI, and there is a different set of legal requirements. For example, the U.S. Federal Communications Commission (FCC) has promulgated several requirements applicable to wireless or mobile telephones (e.g., as set forth in 47 C.F.R. § 20.18), some of which are discussed below:                Basic 911: All 911 calls must be relayed to a call center, regardless of whether the mobile phone user is a customer of the network being used.        E911 Phase 1: Beginning in April 1998, wireless network operators must identify the phone number and cell phone tower used by callers, within six minutes of a request by a PSAP.        E911 Phase 2: Beginning in October 2001, wireless network operators must provide Automatic Location Information (ALI) for 911 calls with the following accuracy:                    Network Based Technology 100 meters for 67% of calls                            300 meters for 95% of calls                                    Handset Based Technology 50 meters for 67% of calls                            150 meters for 95% of calls                                    95% of a network operator's in-service phones must be E911 compliant (“location capable”) by Dec. 31, 2005                        
Thus, for E911 Phase I which began in April 1998, wireless carriers were merely required to provide a PSAP 170 with the phone number of the 911 wireless call originator and identification of the originating cell site 110 and sector (e.g., a street address associated with the receiving cell tower and cell face directional such as NNW, NW, ESE, SE, Omni or Tall, etc.) in the wireless network that handled the 911 call.
At the time of required E911 Phase I compliance, the location of the originating cell site and sector was deemed to provide a sufficient level of location information to allow delivery of the 9-1-1 call to the appropriate PSAP and, through that PSAP, the delivery of emergency services to the caller. E911 Phase II, however, requires that the mobile telephone number and location of the caller be within a specified accuracy margin and delivered to the call taker (e.g., PSAP) in the form of earth coordinates (e.g., latitude and longitude). As will be explained in connection with FIG. 1A, Phase II compliance requires the incorporation of new components and/or operations into the wireless infrastructure to determine and provide the specific location information, as well as for the ability for the call taker (e.g., PSAP) to receive and use the specific location information.
With continued reference to FIG. 1A, wireless network operators can use different wireless E911 solutions to provide voice (e.g., the caller's voice input) and data (e.g., the phone number of a 911 wireless call originator and cell site location information) to a PSAP 160 from their wireless network. One solution (i.e., a Non-Call-path Associated Signaling (NCAS)) uses a mobile positioning center (MPC) 140 to provide data to both a mobile switching center (MSC) 120 and an ALI database 150. The MSC 120, which can also be referred to as a MTSO or MSO, is a switch that serves as an entry point for wireless calls received from multiple cell site sectors into the PSTN. The MSC 120 provides stored program control for wireless call processing, and identifies the switching office that processes the cellular call to the PSTN. The ALI database 150 is a host computer system that stores ALI records to facilitate the display of, for example, a name and address of the wireless service provider or carrier for the phone used to dial 9-1-1 and the callback number, to the call taker or operator at the PSAP 170. In a NCAS solution, calls are routed by two separate paths to the PSAP 170, that is, a voice path and a data path. Voice (e.g., caller voice input) is sent via the voice path from the mobile phone or device (e.g. TCU 100) to the MSC 120 via one or more cell towers 110, and then to a selected PSAP 170 by way of the 911 selective router 160 once an Emergency Service Routing Key (ESRK) is provided from the MPC 140 via the data path as explained below.
For example, the MPC 140 receives the callback number of the calling mobile device 100 and at least Phase I data cell sector location information data from the MSC 120 and generates an ALI record in the ALI database 150 that is indexed via an ESRK assigned to the call. The MPC 140 can provide the ESRK to the MSC 120 via the data path; the MSC 120, in turn, provides the voice call and a routing number (e.g., the ESRK) to the PSAP 170 via the voice path. When the PSAP 170 receives the voice call via the voice path, the PSAP 170 uses the ESRK to retrieve a record from the ALI database 150 that contains the callback number and cell site location.
The MPC 140 can also receive Phase II data (i.e., caller location data comprising latitude and longitude coordinates) and provide it to the PSAP 170 via a record from the ALI database 150. Since Wireless E911 Phase II requires that the specific location of the caller be delivered to the PSAP 170 in the form of earth coordinates (e.g., latitude, longitude or X,Y), a positioning determining entity (PDE) 130 is incorporated into the wireless telephone network infrastructure to perform calculations that identify the geographic location of a mobile unit. The PDE determines the position of a wireless terminal when the mobile device starts a call or while the mobile device is engaged in a call, and can support one or more position determining technologies. The FCC defines two types of position determining technology, that is, network-based and handset-based. Network-based means that the components needed to determine location are embedded into the wireless E911 network, such as at the MSC 120 and/or cell sites 110. Handset-based means that some of the location technology is embedded into the mobile device (e.g., wireless handset) such as a Geographical Positioning System (GPS) chip or software modifications. The PDE receives location data from the base stations 1101-110n and GPS information sources, performs calculations (e.g., using one or more position determining technologies or algorithms), and reports a position point or location (e.g., X,Y) back to the network (e.g., MPC and MSC) for use in the data path described above (e.g., to obtain ESRK from MPC and provide ESRK, callback number and location to the ALI database of the PSAP 150). The GPS coordinates received from a mobile device, however, are often subject to errors and may not result in a very accurate PDE estimated location, even if compared with map database information. Further, network-based position determining technology (e.g., triangulation) may likewise be less accurate than if accurate GPS coordinates could be provided by mobile device.
Phase II solutions provide two alternative methods for determining the PSAP 170 to which a wireless 9-1-1 call will be routed. If coordinates (e.g., X,Y) of the wireless device placing the emergency call are available from the PDE within the requisite routing interval (e.g., 9-1-1 calls are generally routed to a PSAP in 5 seconds or less), those coordinates can be used to determine the appropriate routing of the call. If the coordinates are not available in time to route the call, then routing based on cell site/sector location information as established for Phase I will be used.
The provision of Phase II information (e.g., latitude, longitude coordinates) in the voice path of an E911 call will now be described with reference to FIG. 1B. For example, the mobile device 100 (e.g., a vehicle TCU such as the Ford SYNCH™ unit) can be provided with a Global Positioning System (GPS) receiver to locate the TCU geographically. The Ford SYNCH™ unit has a 911 Assistance application which places a direct call to a local 911 emergency operator in the event of a serious accident with an air bag deployment as indicated at 115. As indicated at 121, the E911 call is routed to the PSAP using Phase I or Phase II data as described above. At 125, a pre-recorded voice message will play when the call is answered which provides a verbal explanation that the vehicle occupants require emergency assistance, and a verbal (e.g., speech synthesized) report of GPS coordinates of the vehicle obtained from the unit's GPS receiver over the voice path. The message can also provide a call taker (e.g., PSAP operator) with instructions to enter a designated DTMF tone to repeat the message with coordinates or to open the voice path (e.g., as indicated at 129, 131 and 133) to allow the 911 operator to communicate directly with the vehicle occupants. As indicated at 127, the PSAP can record the voice accident information from the message (e.g., vehicle coordinates) and use it to dispatch services.
Disadvantages of the wireless E911 solution depicted in FIG. 1A and the TCU 100 described with reference to FIG. 1B are that the TCU location coordinates provided in the voice message in the voice path at 125 may be inaccurate. Also, the MPC 140 may provide the PSAP 170 (e.g., via the ALI database 150) with caller location information via the data path (e.g., using the afore-mentioned network-based means to obtain Phase II data) that conflicts with the information received by PSAP 170 via the voice path.
For example, the TCU GPS receiver generates location information based on the availability of GPS satellites. Increasingly dense urban environments pose a significant problem to navigation systems based on the reception of extremely weak GPS satellite signals. In the event there is substantial blockage of the GPS satellite signals and position cannot be accurately computed (e.g., when driving in tunnels or through urban canyons, or when a mobile TCU is used indoors, etc.), the TCU can rely on GPS assist technology or dead reckoning to estimate the vehicle location. It is possible, however, for errors to be present in the location provided by the TCU using TCU-based GPS assist or dead reckoning.
TCU-based GPS assist technology processes information from multiple sources (e.g., wheel rotation information to estimate distance traveled from the last GPS location, electronic gyroscope information to estimate changes in the vehicle direction, accelerometer, etc.) to estimate the vehicle location. Dead reckoning aids traditional GPS navigation via intelligent algorithms based on a vehicle's distance and directional changes during GPS signal interruption. Dead reckoning or deduced reckoning calculates a user's or vehicle's current position using a previously determined position (e.g., GPS fix) and advances that position using known or estimated speeds (e.g., using sensors such as pedometer, accelerometer, wheel tick counter, and so on) over elapsed time and course. Thus, errors may be present in the location provided by the TCU using TCU-based GPS assist or dead reckoning due to an inaccurate estimate of distance traveled, direction traveled, or both from the last reliable GPS fix. For instance, vehicle distance errors may be caused by an inaccurate estimate of the tire diameter applied to the rotation information received from the wheel tick counter.
TCU-based GPS assist algorithms normally calibrate tire diameter by measuring wheel revolutions and distance traveled while the GPS signal is strong to allow for accurate estimations when GPS signal is weak. Direction errors are more problematic due to drift rates of the electronic gyroscope technology provided in the vehicle. For example, if a driver in an urban canyon turns and then stops due to traffic, and the gyroscope drifts by 8 degrees during the turn, the new heading will be off by 8 degrees. If the driver continues straight for another ⅓ of a mile, the TCU estimated location will be off by a city block.
Vehicle navigation systems usually mitigate this problem by adjusting the new heading to keep the vehicle path fixed based on street coordinates defined in a navigation system map database in the TCU, thereby preventing the vehicle track to drift to an adjacent street. Although combining wheel rotation and gyroscope information with a map database can be an effective solution for improving the accuracy of the location estimation, the map databases can be expensive. Thus, it may not be cost effective to integrate a map database into TCUs.
Accordingly, some telematics service providers (TSP) such as OnStar Corporation manage dedicated call centers with trained operators for handling automated accident notification calls from their subscribers. These call centers are equipped to receive custom data messages from the TCU in addition to vehicle location, such as accident severity, number of vehicle occupants, vehicle roll over and other information that may be available from vehicle sensors. Operators at the TSPs are trained to communicate with the vehicle occupants, contact the appropriate PSAP to transfer the accident information, and ensure that the proper emergency services are dispatched. Dedicated call centers also improve the accuracy of the reported TCU location by post-processing, for example, the latitude and longitude coordinates, that is, reverse geocoding the latitude and longitude coordinates against map data to locate a street address (e.g., using a locally stored map database to assign a non-location value such as a street address to latitude and longitude coordinates), which is a more cost effective approach than integrating a map database in the TCU.
Although dedicated emergency call centers set up by TSPs can be effective, costs associated with establishing and maintaining call centers to provide the automated collision notification (ACN) service can be prohibitively expensive. For example, to recover the call center costs, TSPs must charge subscribers higher fees for the automated accident notification service, which reduces the number of drivers capable of paying for the service.
A need therefore exists for a method and system for providing improved caller location data for use by E911 systems, and without requiring, for example, commercial call centers or map databases in the TCU. Further, a need exists for a method and system that reduces the likelihood that a PSAP or other answering point receives conflicting location information from network-based and TCU-based location information sources. Such conflicting location information results in different location data being received on the voice and data paths of a wireless E911 system, which can impair a PSAP operator's reaction time and decision-making abilities when processing an E911 call and therefore delay the dispatch of emergency responders and their operations.
Further, a need exists for providing accurate E911 Phase II location information to PSAPs that may not be equipped to receive it. PSAPs have the financial resources to provide E911 Phase II services. Since they are generally constrained by municipal or government agency budgets and funding measures, and they are not required by the FCC to fulfill the FCC requirements, a number of PSAPs do not have the Phase II capability to receive location coordinates from the cellular infrastructure.
For example, some PSAPs operator terminals are not able to display location coordinates, which can occur when the ALI format in the PSAPs existing ALI database has not been modified to allow display of latitude and longitude coordinates on the PSAPs operator terminal screen. Some PSAPs do not have the capability of communicating with a MPC 140 and its data path to receive an ALI push (e.g., ESRK, location information and callback number to store in the ALI database 150) for later access by the PSAP with the ESRK received via the voice path. In such instances, the caller's voice and callback number are delivered to the PSAP via the voice path only, that is, MSC forwards the callback number along with the voice using a routing number called an emergency services routing digit (ESRD) that mimics an ANI for 911 call routing (e.g., the ESRD is pre-provisioned in the 911 selective router 160 and the ALI database 150 to route a call based on the cell sector that received it), and no other location data is sent to the PSAP. Thus, a need exists for a method and system for allowing caller location information or other telematics safety and/or security services (TSSS) information to be transferred in a voice path to the PSAP during an E911 call, for example, to guarantee that TCU location coordinates can be relayed to PSAPs lacking Phase II capabilities.